That can't "maintain the head angle". While I understand that it stays parallel, as the fork goes through the travel, the head angle will drop as it does on any other bike,thus changing the head angle.
Great video, such skill for a kid, even in this you could see his potential. Shame he didn't have a Twist Bike, it would have grown with him and he wouldn't have needed to switch to a pedal bike. twistbikes.com